Kreutter/Costello: DC Circuits 2 Learning the Language for DC Circuits 2.1 Circuit Diagrams A circuit diagram is a representation that uses symbols to show the components in a circuit and how they are connected: Part of Circuit Wire Sketch Schematic Symbol Ammeter (reads current) 1 L Voltmeter (reads voltage) Resistor -J Light Bulb () : Battery Ground Use the symbols to draw a circuit for a battery, a light bulb, and a single wire. Make sure the diagram represents a circuit that would result in a light bulb being lit! ter/Costello: DC Circuits 2 • _.2 Vocabulary liv i. Potential Difference (voltage): be ç 4i ç 4 : f: 4 r f’c 3, • “F ‘WI V K I ., t i Current: ntist 3, Y -4’ () .1 ‘ 4 4W, I )t , I C flu Resistance: •(4- i I ‘j• (1 I 1 Series Circuit: ‘F I ‘I I a u-tv S p. ‘j 1 14 I Parallel Circuit: 0 1’ 34 •1 1eutter/Coste11o: DC Circuits 2 2.3 We connected can that learned to explain the and Parts of the Electric Circuit Battery for light predict a bulb light with phenomena bulb to glow, conducting related the wires. to poles two Come electric up of with battery must analogies that a circuits. Create your own analogy ?urp Connecting wires W6C Moving Electrons : I t1 Light bulb, resistor t’ic Observed properties of electric circuit Observed properties of your own analogy When resistors are in series (and you don’t the voltage), change current When gIown. resistors are in (and you don’t change the voltage), current ç up. parallel V ITh) I — be eutter/Coste1lo: DC Circuits 2 2.4 Test your Ideas For each of the following circuits below; predict the brightness of the bulbs. Identify each circuit as series or parallel. Then, build the circuits using real materials. Are the results consistent with the predicted outcome? Explain the results using any of your analogies of electric phenomena. (b) (c) (e) (d) 3 Circuit a Results Prediction Explanation t ‘ b r 4 - C R 0 v : I 0 — L isfr r * ;; -F e •reutter/Costello: DC Circuits 2 2.5 Reason (a) Consider the following partial circuit diagrams below, and indicate whether components between point A and point B are in parallel or in series: A I1 B A I ±± I AB B B — F _; Consider the circuit drawn below, including batteries A and B and the three light bulbs: B A (b) Indicate two sets of components (pieces) that are each connected in series. (c) Indicate at least one set of components (pieces) that are each connected in parallel (4) : 2.6 Represent and Reason (a) Predict how the brightness of the top bulb shown in the illustration to the right changes when you close switch 1. a_i 2 (b) Predict how the brightness of the top bulb changes when you close switch 2 (switch 1 is open). (c) Rate the brightness of the three bulbs when both of the switches are closed. Explain your reasoning using any of the analogies.